Electric School Bus with ZEBRA Battery and Integrated Fast Charge

This page updated November 23, 2005.

Sacramento Municipal Utility District

Electric School Bus with ZEBRA Battery
and Integrated Fast Charge

CARB Grant Number ICAT 01-1

The statements and conclusions in this Report are those of the grantee and not necessarily those of the California Air Resources Board. The mention of commercial products, their source, or their use in connection with material reported herein is not to be construed as actual or implied endorsement of such products.

Project Summary
In this project, an advanced battery system and an advanced drive were integrated into an existing 1997 BlueBird electric school bus. The installed system addressed the performance, range, reliability, and cost barriers that limited the market place success of earlier efforts to field electric busses. This project shows how a currently available battery and drive system technology is being used to reliably provide school bus service.
The bus utilizes a Sodium Nickel Chloride ZEBRA battery, advanced Siemens Drive System, and modern CAN Bus linked microprocessor control for a very high level of integration. The possibilities for cost reduction and performance improvements with this control scheme have only begun to be realized. This bus addresses all of the market barriers encountered by early BlueBird TCEV 2000 electric school busses originally fitted with lead acid batteries and Northrup Grumman drive systems
Operation of the ZEBRA bus had been reliable and economical. Energy consumption has been better than 15 miles per diesel-equivalent gallon, and maintenance costs have been lower than expected for a first of a kind development prototype. Most of the problems encountered with the original bus design have been addressed through three main elements that are:
  • Improved System Integration Through Microprocessor Control and CAN Bus Communication,

  • High Performance, High Efficiency, Software Driven Traction Drive and Charging System,

  • Improved Battery Technology with Integrated Battery Management and Control.
As of April 2004 the bus has been fielded for 14 months and 9,936 miles. The bus has provided regular service, completing both a morning trip and an afternoon trip picking up and delivering students to Napa Valley Unified School District.
The performance of this bus should be monitored in the future to verify the actual life and aging characteristics of the system. As of this writing, the bus appears to perform its mission with ease. During extended service of this bus, opportunities to document maintenance experiences and procedures could prove extremely valuable for future training of maintenance personnel. In addition, these records would be invaluable in assessing the actual life cycle cost of this bus system. It is noted that cycle life of 2,500 cycles was listed in Table 1 for Ni-MH batteries. This exceeds the expectation for those batteries derived from early experience. Will the ZEBRA bus exceed the guarantee? What effect will the shallow discharge cycles have on the batteries ultimate life? Continued operation will answer these questions. It is our hope that efforts to maintain the bus and find these answers continue at Napa Valley Unified School District.
The ZEBRA Electric School Bus Project was accomplished with funding from the California Air Resources Board under ICAT Grant 01-1. Other project partners included U.S. DOT Research and Special Projects Administration, Santa Barbara Electric Bus Works.
Electric Busses have a tremendous potential to improve energy efficiency and to provide the cleanest possible transportation for our children. Additional effort to develop this technology and to educate industry and policy makers is warranted. The following figure shows the bus as deployed in the Napa Valley Unified School District last.

Funding Source

Funding Amount




$  40,065

U.S. Department of Transportation,
MES-DEA, Napa Valley Unified
School District


Click here for the entire final report.

ICAT Funded Projects